I must have a mental block.
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From: Tim Perry on 17 Jul 2010 09:40 > > It is all they could afford, and even that was a struggle. It is to be > used only for announcments and some background music. I use sp4's with a > yamaha 16 and a QSC 1800 and the chamber's little setup sounds as good as > mine inside their little building. Mainly I suppose because I have to have > mine set so low to keep from rattling the metal rafters and roof. <G> > > The reason for all of this discussion is because in the owners manual for > the speakers, they show, on page 5, a picture in which they are running 4 > B215XL's. They didn't pay any attention to the fact that picture shows > them running out of a Europower EP2000. So, anyhow, when they called and > asked, I just wanted to make sure I was on solid ground when I answered > their questions. I've told them before that this was not a good idea, but > I just wasn't all that sure of myself. So, thanks to all for the > education. > > > -- > Careful how you respond. I have people! > > JC Wire the speakers in series/parallel for an 8 ohm load
From: The Post Quartermaster on 17 Jul 2010 12:08 "Tim Perry" <timperry(a)donespameroadrunner.com> wrote in message news:i1sbrq$vji$1(a)news.eternal-september.org... > > >> It is all they could afford, and even that was a struggle. It is to >> be used only for announcments and some background music. I use >> sp4's with a yamaha 16 and a QSC 1800 and the chamber's little >> setup sounds as good as mine inside their little building. Mainly I >> suppose because I have to have mine set so low to keep from >> rattling the metal rafters and roof. <G> >> >> The reason for all of this discussion is because in the owners >> manual for the speakers, they show, on page 5, a picture in which >> they are running 4 B215XL's. They didn't pay any attention to the >> fact that picture shows them running out of a Europower EP2000. So, >> anyhow, when they called and asked, I just wanted to make sure I >> was on solid ground when I answered their questions. I've told them >> before that this was not a good idea, but I just wasn't all that >> sure of myself. So, thanks to all for the education. >> >> >> -- >> Careful how you respond. I have people! >> >> JC > > Wire the speakers in series/parallel for an 8 ohm load > That's something I intend to try. Thanks, -- Careful how you respond. I have people! JC
From: liquidator on 17 Jul 2010 17:41 "Krooburg Science" <krooburg(a)gmail.com> wrote in message news:b6655c0d-5d42-481a-9cc9-92a6ac196193(a)z34g2000pro.googlegroups.com... On Jul 16, 12:09 pm, "The Post Quartermaster" <quartermasterextraordina...(a)postfiftyone.org> wrote: > I've never quite caught on to the Ohms thing. If I am running two > speakers (I forget the terminology - series or parallel) in a system > in which the speaker cable runs from the power amp to the first > speaker, and then another cable runs from that speaker to the second > speaker, what must I calculate in order to safely run yet another > cable from the second speaker to a third speaker? > -- > Careful how you respond. I have people! > > JC Daisy chaining speakers is a *parallel* connection which is electrically the same connection is hooking all the speakers directly to the amp terminals. The disadvantage to daisy chaining is that cable resistance is higher and electrical damping is lower since all the speakers go through a single cable to the amp. Anyhow, every time you take two identical speakers (loads) and connect them in parallel to the amp by either method, you effectively cut the impedance of the load that the amp "sees" in half. So two 8� speakers nets a 4� nominal load - nominal meaning average. Speaker impedance varies with frequency which can be very important depending on the amp and how well it can handle dips in impedance below nominal. Now adding a 3rd speaker requires the use of a formula since you're dealing with an odd number. The formula is Rt = 1 / [ (1/R1) + (1/R2) + (1/R3). I suffices to say that the load with three 8� speakers is ~2.66�. If your amp channel is rated to handle 2 ohm loads (four 8� speakers in parallel or two 4 ohm speakers in parallel), then 2.66� should work fine. If it's rated for 4� minimum, don't do it. - K Quick and dirty for the math impaired, if the same just divide the original impedance by number of speakers...ie 8/2=4 8/3=2.66 8/4=2
From: Rupert on 17 Jul 2010 18:10 On Jul 17, 2:41 pm, "liquidator" <mi...(a)mad.scientist.com> wrote: > "Krooburg Science" <kroob...(a)gmail.com> wrote in message > > news:b6655c0d-5d42-481a-9cc9-92a6ac196193(a)z34g2000pro.googlegroups.com... > On Jul 16, 12:09 pm, "The Post Quartermaster" > > <quartermasterextraordina...(a)postfiftyone.org> wrote: > > I've never quite caught on to the Ohms thing. If I am running two > > speakers (I forget the terminology - series or parallel) in a system > > in which the speaker cable runs from the power amp to the first > > speaker, and then another cable runs from that speaker to the second > > speaker, what must I calculate in order to safely run yet another > > cable from the second speaker to a third speaker? > > -- > > Careful how you respond. I have people! > > > JC > > Daisy chaining speakers is a *parallel* connection which is > electrically the same connection is hooking all the speakers directly > to the amp terminals. The disadvantage to daisy chaining is that cable > resistance is higher and electrical damping is lower since all the > speakers go through a single cable to the amp. Anyhow, every time you > take two identical speakers (loads) and connect them in parallel to > the amp by either method, you effectively cut the impedance of the > load that the amp "sees" in half. So two 8Ù speakers nets a 4Ù nominal > load - nominal meaning average. Speaker impedance varies with > frequency which can be very important depending on the amp and how > well it can handle dips in impedance below nominal. Now adding a 3rd > speaker requires the use of a formula since you're dealing with an odd > number. The formula is Rt = 1 / [ (1/R1) + (1/R2) + (1/R3). I suffices > to say that the load with three 8Ù speakers is ~2.66Ù. If your amp > channel is rated to handle 2 ohm loads (four 8Ù speakers in parallel > or two 4 ohm speakers in parallel), then 2.66Ù should work fine. If > it's rated for 4Ù minimum, don't do it. > > - K > > Quick and dirty for the math impaired, if the same just divide the original > impedance by number of speakers...ie 8/2=4 8/3=2.66 8/4=2 Thanks for tip Liquid. That does simplify things. Rupert
From: The Post Quartermaster on 17 Jul 2010 20:43
"Rupert" <foodsteaks(a)gmail.com> wrote in message news:ca82262e-2262-4349-8223-996d839fe684(a)z15g2000prn.googlegroups.com... On Jul 17, 2:41 pm, "liquidator" <mi...(a)mad.scientist.com> wrote: > "Krooburg Science" <kroob...(a)gmail.com> wrote in message > > news:b6655c0d-5d42-481a-9cc9-92a6ac196193(a)z34g2000pro.googlegroups.com... > On Jul 16, 12:09 pm, "The Post Quartermaster" > > <quartermasterextraordina...(a)postfiftyone.org> wrote: > > I've never quite caught on to the Ohms thing. If I am running two > > speakers (I forget the terminology - series or parallel) in a > > system > > in which the speaker cable runs from the power amp to the first > > speaker, and then another cable runs from that speaker to the > > second > > speaker, what must I calculate in order to safely run yet another > > cable from the second speaker to a third speaker? > > -- > > Careful how you respond. I have people! > > > JC > > Daisy chaining speakers is a *parallel* connection which is > electrically the same connection is hooking all the speakers > directly > to the amp terminals. The disadvantage to daisy chaining is that > cable > resistance is higher and electrical damping is lower since all the > speakers go through a single cable to the amp. Anyhow, every time > you > take two identical speakers (loads) and connect them in parallel to > the amp by either method, you effectively cut the impedance of the > load that the amp "sees" in half. So two 8� speakers nets a 4� > nominal > load - nominal meaning average. Speaker impedance varies with > frequency which can be very important depending on the amp and how > well it can handle dips in impedance below nominal. Now adding a 3rd > speaker requires the use of a formula since you're dealing with an > odd > number. The formula is Rt = 1 / [ (1/R1) + (1/R2) + (1/R3). I > suffices > to say that the load with three 8� speakers is ~2.66�. If your amp > channel is rated to handle 2 ohm loads (four 8� speakers in parallel > or two 4 ohm speakers in parallel), then 2.66� should work fine. If > it's rated for 4� minimum, don't do it. > > - K > > Quick and dirty for the math impaired, if the same just divide the > original > impedance by number of speakers...ie 8/2=4 8/3=2.66 8/4=2 Thanks for tip Liquid. That does simplify things. Rupert I don't remember if their set up has a monitor output. But if it does, wouldn't it work if I ran out of the monitor output into another power amp out to a couple of outside speakers? I know back in the old days (I'm pushing 70) we daisy chained power amps a few times. Frankly, I don't remember that accomplishing anything though. -- Careful how you respond. I have people! JC |